Merge branch 'qa-quarantine-failing-staging-nightly-tests' into 'master'

Quarantine failing tests

See merge request gitlab-org/gitlab-ce!27036

(cherry picked from commit 88bf73a7)

fcc7b72b Quarantine failing tests

qa/qa/specs/features/browser_ui/4_verify/ci_variable/add_ci_variable_spec.rb

 # frozen_string_literal: true
 module QA
-  context 'Verify' do
+  # Failure issue: https://gitlab.com/gitlab-org/quality/nightly/issues/91
+  context 'Verify', :quarantine do
     describe 'CI variable support' do
       it 'user adds a CI variable' do
         Runtime::Browser.visit(:gitlab, Page::Main::Login)